As 70% of potable water on the planet is used in agriculture, alternatives are needed to reduce itsconsumption and optimize the use of water for cultivation. Hydrogels are hydro polymers capable of absorbinglarge quantities of water and have been used as an alternative to improve water storage in areas of shortage.This study aimed to assess the use of different doses of hydrogels for water storage in soil, emphasizing theadvantages and disadvantages of each dose. The doses of the hydrogel used were (4, 8 and 12 g per pot) to analysethe efficiency of the product compared to the control, depending on the availability of moisture and increase inelectrical conductivity. These variables were determined with the use of time-domain reflectometer (TDR) probe.The dose of 4 g per pot was more viable, compared to the manufacturer’s recommendation (8 g per hole, underfield conditions), because it presented similar moisture content, lower electrical conductivity and lower cost.The higher dose (12 g per pot) caused swelling of the soil resulting in loss of product and soil and possible rootstrangulation. | Frente ao uso de 70% de água potável do planeta que a agricultura consome, alternativas são necessáriaspara reduzir o consumo e otimizar o uso da água durante o cultivo. Os hidrogeis são polímeros hidrorretentorescapazes de absorver grande quantidade de água e estão sendo utilizados como alternativa viável para melhoraro armazenamento de água em áreas de escassez. O presente trabalho teve como objetivo avaliar a utilização dediferentes dosagens de hidrogel no armazenamento de água no solo destacando-se as vantagens e desvantagensde cada dosagem. Utilizaram-se três diferentes dosagens do hidrogel (4, 8 e 12 g por vaso com 8 kg de solo)permitindo analisar a eficiência do produto comparado à testemunha em função da disponibilidade de águae do aumento da condutividade elétrica do solo. Essas variáveis foram determinadas com o uso de sondas dereflectometria no domínio do tempo (TDR). A dosagem de 4 g por vaso mostrou-se viável pois comparada àrecomendação do fabricante (8 g por cova, em condições de campo), apresentou teor de água semelhante, menorcondutividade elétrica do solo e menor custo de implantação. A maior dosagem (12 g por vaso) causou inchaço dosolo acarretando em perda do produto, solo e possível estrangulamento radicular.

The purpose of this study was to evaluate the uniformity of distribution coefficient (UDC) and coefficient of variation (CV) of a familiar set of irrigation, classifying it the ASAE standard. The irrigation and fertigation are determined by two methods the KELLER & KARMELI and DENÍCULI . The two experiments were subjected to varying pressures: 12, 14, 16 and 18 kPa, in a completely randomized design of twenty samples composed of flows with three replications. Urea, potassium chloride (KCl) and ammonium phosphate (MAP) were the elements used for fertigation. The system consisted of a 200 L tank, which supplied another container of 30 L, it was moved vertically to control the pressure. The data was statistically compared between treatments for each methodology. In fertigation the best pressure was 16 kPa and was classified as "excellent" for UDC (91.03%) and "marginal" for C.V. (7.47%). For the irrigation treatment, the best pressure was 16 kPa rated "excellent" for UDC (91.2%) and "marginal" for C.V. (7.68%). The DENÍCULI et al. (1980) methodology proved more reliable for the evaluation of drip systems. It was observed that this set has good uniformity of distribution, but with great variability in flows.<br>O objetivo deste trabalho foi avaliar o coeficiente de uniformidade de distribuição (CUD) e o coeficiente de variação (C.V.) de um conjunto de irrigação familiar, classificando-o pela norma ASAE (American Society of Agricultural Engineers), nos sistemas de irrigação e fertirrigação, sendo determinados por duas metodologias: a de KELLER & KARMELI, e a de DENÍCULI. Os dois experimentos foram submetidos a quatro pressões: 12; 14; 16 e 18 kPa, em um delineamento inteiramente casualizado de vinte coletas de vazões, com três repetições. Para a fertirrigação, foram utilizados ureia, cloreto de potássio (KCl) e fosfato monoamônico (MAP). O sistema era composto por um reservatório de 200 L, que abastecia outro recipiente de 30 L, este sendo deslocado verticalmente para o controle da pressão. Os dados foram comparados estatisticamente entre os tratamentos para cada metodologia. Na fertirrigação, a melhor pressão foi de 16 kPa, e classificou-se como "excelente" para CUD (91,03%) e "marginal" para C.V. (7,47%). Para o tratamento com irrigação, a melhor pressão foi de 16 kPa classificado como "excelente" para CUD (91,2%) e "marginal" para C.V. (7,68%). A metodologia de DENÍCULI et al. (1980) mostrou-se mais confiável para a avaliação de sistemas de gotejamento. Observou-se que este conjunto tem ótima uniformidade de distribuição, mas com grande variabilidade nas vazões.

We analyzed the concentration of dissolved trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb) in the water column of Reloncaví Fjord. Sampling was performed during the CIMAR 12 Fiordos cruise in 2006. A total of 36 passive samplers or DGTs (diffusion gradient in thin films) were anchored at four stations along the longitudinal axis of the fjord. The DGTs were deployed at three depths per station and left there for 48 h. The metal contents on each thin film were analyzed using inductively coupled plasma atomic emission spectroscopy. Concentrations were highest in the surface layer at the head of the estuary, which is directly influenced by Petrohué River. Characteristic sequences of the studied metals were defined in the area with the greatest continental influence (Z(5-25m) = Cu >Mn> Fe > Ni >Pb> Cr > Cd > Co) and in the area with a marine or coastal influence (Z(5-25m) = Fe > Cu>Mn> Ni >Pb> Cr > Cd > Co). A similar metal sequence was found in the deepest layer: Z(40-m) = Fe >Mn> Cu >Pb> Ni > Cd > Cr > Co. The passive sampling technique using DGTs to determine dissolved trace metals in the sea water provided robust information on the concentrations of the ten metals analyzed.<br>Se analiza la concentración de metales trazas disueltos (Cd, Co, Cr, Cu, Fe, Mn, Ni y Pb), en la columna de agua del fiordo Reloncaví. El muestreo se realizó durante la campaña CIMAR 12 Fiordos, 2006. Para ello se fondeó en cuatro estaciones y en tres profundidades, un total de 36 muestreadores pasivos o DGT (láminas de gradiente de difusión) a lo largo del eje longitudinal del fiordo, durante 48 h. El contenido de metales en cada lámina fue analizado mediante espectroscopía de emisión atómica con acoplamiento inductivo de plasma. Las mayores concentraciones se observaron en la superficie de la columna de agua, en la cabeza del estuario, directamente influenciada por el río Petrohué. Se definió para el área una secuencia de los metales estudiados característica, para la zona de mayor influencia continental: Z(5-25m) = Cu > Mn > Fe > Ni > Pb > Cr > Cd > Co y para la zona de influencia marina o costera: Z(5-25-m) = Fe > Cu > Mn > Ni > Pb > Cr > Cd > Co, observándose una secuencia semejante para los metales analizados en la capa de mayor profundidad: Z(40 m) = Fe > Mn > Cu > Pb > Ni > Cd > Cr > Co. La técnica de muestreo pasiva, con DGTs, para la determinación de metales traza disueltos en agua de mar, permitió obtener información robusta de las concentraciones de los diez metales analizados.

In order to know the susceptibility to carbapenems (imipenem and meropenem), ceftazidime and aztreonam as phenotypical indicator substrates of β–lactamases, 30 strains of Pseudomonas aeruginosa (18 from animal clinical samples and 12 from non–chlorinated water) were analysed. There were not synergism indicating their production, and the results differ from those of human where prevalence of resistance is a great problem when instauring treatment. | Con el fin de conocer la sensibilidad a carbapenems (imipenem y meropenem), ceftazidime y aztreonam como indicadores fenotípicos de sustratos de β–lactamasas, se analizaron 30 cepas de Pseudomonas aeruginosa (18 de muestras clínicas animales y 12 de aguas no clorinadas). No se halló sinergismo indicador de su producción. Estas estirpes se diferencian de las aisladas de seres humanos, donde alcanzan un alto grado de resistencia que dificulta considerablemente el tratamiento.

El objetivo de esta investigación fue estudiar en condiciones de hidroponía e invernadero, el efecto de dos niveles de humedad aprovechable del sustrato en plantas de jitomate (Solanum lycopersicum L), mediante la técnica de riego secado parcial de la raíz (SPR). Para ello se evaluaron variables fisiológicas (materia seca de hoja, tallo, raíz y fruto, relaciones hídricas, intercambio de gases, rendimiento), calidad de fruto (firmeza, sólidos solubles totales, pH y conductividad eléctrica), y la eficiencia del uso de agua. El experimento se estableció en Lomas de San Esteban, Texcoco, Estado de México, en 2006. Las plantas crecieron en contenedores de volumen homogéneo, con tezontle, la raíz se dividió en dos partes, y se aplicaron dos tratamientos de humedad aprovechable (HA) residual en el sustrato, testigo: 80%≤HA≤ 100% y 80%≤HA≤ 100% y SPR: 80%≤HA≤ 100% y 30%≤HA≤ 100%. Estos tratamientos se iniciaron 28 días después del transplante y se mantuvieron hasta el final del experimento. Los resultados obtenidos indicaron que el tratamiento SPR mostró diferencias estadísticas significativas (p≤ 0.05), respecto al testigo, en relación con la tasa de fijación de CO2 (SPR, 17.67 y testigo 9.23 µmol m² s¹) a 86 días de haber iniciado los tratamientos (DDIT), volumen evapotranspirado por planta durante todo el experimento (SPR 186.7 L y testigo 229 L), la calidad de fruto incrementó: firmeza 25%, los sólidos solubles totales 13% y la conductividad eléctrica 13%, respecto al testigo; y la eficiencia en el uso del agua (EUA) con base en la materia seca incrementó 29% y EUA instantánea fue de 57, 61 y casi 100%, respecto al testigo, a los 65, 80 y 86 DDIT respectivamente, sin afectar el rendimiento (SPR 363.2 g y testigo 345.8 g) y el potencial total del agua (SPR -0.54 y testigo -0.57; SPR -0.46 y testigo -0.55 MPa), a los 79 y 118 DDIT respectivamente. | The aim of this research was to study in hydroponics and greenhouse conditions the effect of two levels of usable moisture from the substrate in tomato plants (Solanum lycopersicum L.), by the irrigation technique of partial root drying (PRD). For that, physiological variables were evaluated (dry matter of leaf, stem, root and fruit, water relations, gas exchange, yield), fruit quality (firmness, total soluble solids, pH and electrical conductivity) and the efficiency of water use. The experiment was done in Lomas de San Esteban, Texcoco, Mexico State in 2006. Plants grew in homogeneous volume containers with tezontle, the root was divided in two parts and two available moisture (AM) treatments were applied residual in substrate, control: 80%≤AM≤ 100% and 80%≤AM≤ 100% and PRD: 80%≤ AM≤ 100% and 30%≤ AM≤ 100%. The treatments started 28 days after transplantation and continued until the end of the experiment. Results indicated that PRD treatment, showed statistically significant differences (p≤ 0.05) than the control, in relation to CO2 fixation rate (PRD, 17.67 and control 9.23 µmol m² s¹) at 86 days of initiating the treatment (DAIT), evapotranspirated volume per plant throughout the experiment (PRD 186.7 L and control 229 L), fruit quality increased: firmness 25%, total soluble solids 13% and electrical conductivity 13%, compared with control; efficiency in water use (EWU) based on dry matter increased by 29% and instantly EWU was 57, 61 and almost 100% respect to the control at 65, 80 and 86 DAIT respectively, without affecting yield (PRD 363.2 g and control 345.8 g) and total water potential (PRD -0.54 and control -0.57; PRD -0.46 and control -0.55 MPa), at 79 and 118 DAIT respectively.

7 pages, 3 figures, 1 table.-- PMID: 19080927 [PubMed]. | [ESP] Objetivos: La cloración del agua da lugar a la formación de subproductos potencialmente dañinos para la salud, entre ellos los trihalometanos, que se han hallado elevados en algunas zonas de España. En este estudio se investigan los valores de trihalometanos en el agua de consumo suministrada por varios sistemas de abastecimiento de la provincia de Granada, en el área de actuación de la cohorte madres-hijos de la Red INMA (Infancia y Medio Ambiente). | Métodos: Se analizaron 82 muestras de agua de consumo en dos campañas de muestreo en invierno y verano de 2006. Se determinó la concentración de cloroformo, romodiclorometano, dibromoclorometano y bromoformo, siguiendo un procedimiento optimizado basado en cromatografía de gases y espectrometría de masas. | Resultados: El rango de concentración de trihalometanos totales se situó entre 0,14 y 18,75 ug/l en la campaña de invierno y entre 0,01 y 31,87 ug/l en la de verano. El compuesto mayoritario fue cloroformo. La concentración media de trihalometanos en agua de origen superficial y subterráneo fue de 10,13 y 1,41 ug/l, respectivamente. | Conclusiones: Los valores de trihalometanos encontrados son muy inferiores a la concentración máxima admisible (100 ug/l) establecida por la Unión Europea para estos compuestos. Estos valores varían significativamente según el origen del agua, con mayores concentraciones en áreas urbana y semiurbana, donde el agua es mayoritariamente de origen superficial. La presencia de trihalometanos en la zona es menor a la descrita en otras regiones españolas. | [ENG] Objectives: Drinking water chlorination generates potentially harmful by-products, such as trihalomethanes. Trihalomethane levels are high in some parts of Spain. The aim of the present study was to investigate trihalomethane concentrations in drinking water from distinct water supplies in the province of Granada, within the framework of the Childhood and Environment (INMA) study. | Methods: Eighty-two tap water samples were collected in two campaigns during the winter and summer of 2006. An optimized procedure based on gas chromatography and mass spectrometry was used to determine concentrations of chloroform, bromodichloromethane, dibromochloromethane, and bromoform in the samples. | Results: Total trihalomethane concentrations ranged from 0.14 to 18.75 ug/l in winter samples and from 0.01 to 31.87 ug/l in summer samples. The most abundant compound was chloroform. Mean trihalomethane concentrations were 10.13 in surface waters and 1.41 ug/l in ground waters. | Conclusions: The trihalomethane levels found were considerably below the maximum permitted level of 100 ug/l in the European Union. The values obtained varied widely according to the type of water source: the highest concentrations were found in urban and sub-urban areas, where the water is largely of surface origin. The presence of trihalomethanes was lower than that reported in other Spanish regions. | Este trabajo se ha financiado gracias a los proyectos de investigación subvencionados por la Comisión Europea (Environmental Reproductive Health-QLK4-1999-01422), el Fondo de Investigaciones Sanitarias (Red de Infancia y Medio Ambiente, INMA-G03/176) y la Consejería de Salud de la Junta de Andalucía (SAS-202/04). | Peer reviewed

&lt;!-- @page { margin: 2cm } --&gt; &lt;p class="western" align="justify"&gt;A line source with a five-band irrigation experiment was used to determined the total common bean water demand under conventional and no-tillage systems. Irrigation was controlled by two tensiometer sets installed in the second band parallel to the line source. The no-tillage system resulted in a 20% reduction in irrigation water demand as compared to the conventional system. The total estimated demand based on the class “A” evaporation tank overestimated the tensiometer determined demand for conventional and no-tillage systems by 11% and 29%, respectively.&lt;/p&gt; &lt;p class="western"&gt;KEY-WORDS: No-tillage; tensiometer; irrigation.&lt;/p&gt;<br>&lt;!-- @page { margin: 2cm } --&gt; &lt;p class="western" align="justify"&gt;Em um experimento com cinco faixas de irrigação, obtidas por uma linha central de aspersão, determinou-se a demanda total de água do feijoeiro nos sistemas de plantio convencional e direto. O controle da irrigação foi feito por duas baterias de tensiômetros instaladas na segunda faixa paralela à linha de aspersão. O sistema de plantio direto proporcionou economia de 20% de água de irrigação em relação ao plantio convencional. A demanda total estimada com base na evaporação do tanque classe “A”, superestimou em 11,0% e 29,0% a demanda determinada por tensiometria para os sistemas de plantio convencional e direto, respectivamente.&lt;/p&gt; &lt;p class="western" align="justify"&gt;PALAVRAS-CHAVE: Plantio direto; tensiômetro; irrigação.&lt;/p&gt;